Add main-branch changelog stubs

CHANGELOG.md

@@ -0,0 +1,8 @@
+# See elsewhere for changelog
+
+This project’s release notes are curated from the Git history of its main
+branch. You can find them by looking at [the version of this file on the
+`release` branch][branch] or the [GitHub release history][gh-releases].
+
+[branch]: https://github.com/WorldWideTelescope/wwt-jupyterlab/blob/release/CHANGELOG.md
+[gh-releases]: https://github.com/WorldWideTelescope/wwt-jupyterlab/releases

wwt_jupyterlab_extension/CHANGELOG.md

@@ -0,0 +1,8 @@
+# See elsewhere for changelog
+
+This project’s release notes are curated from the Git history of its main
+branch. You can find them by looking at [the version of this file on the
+`release` branch][branch] or the [GitHub release history][gh-releases].
+
+[branch]: https://github.com/WorldWideTelescope/wwt-jupyterlab/blob/release/wwt_jupyterlab_extension/CHANGELOG.md
+[gh-releases]: https://github.com/WorldWideTelescope/wwt-jupyterlab/releases

wwt_jupyterlab_extension/MANIFEST.in

@@ -1,3 +1,4 @@
+include CHANGELOG.md
 include LICENSE
 include README.md
 include install.json